Electric circuit breaker



April 14, 1,942. H. THOMMEN ELECTRIC CIRCUT BREKER Filed Feb. 8, 1940 Patented Apr. 14, 1942 ELECTRIC CIRCUIT BREAKEE Hans Thommen, Baden, Switzerland, alaignor to Aktiengesellschaft Brown, Boveri a Cie., Baden.

Switlerland Application February 8, 1940, Serial No. 317,948 In Germany May 27, 1938 (Cl. 20G- 148) 13 Claims.

With circuit 'breakers having two or more points of interruption per po1e,.it can generally be observed that the distribution of the voltage over the diierent points oi' interruption when rupturing the arc is unequal.v This unequal voltage distribution over several places oi' interruption is particularly a disadvantage in circuit breakers having contact places subjected to an air pressure blast, because their interruptive capacity is thus considerably reduced.

The invention relates to a switching arrangement in which two circuit interrupters are connected in series. one circuit interrupter being a multiple break gas blast circuit breaker which connects a' damping impedance into the circuit to reduce the current flow, and the other circuit interrupter being a disconnecting switch for interrupting the residual current ow through the damping impedance.

In accordance with the invention, the current reducing damping devices, in order to achieve an equal voltage distribution over all places of interruption of the power circuit breaker, are so selected and dimensioned that an air disconnect switch in series with the gas blast circuit breaker may be employed for the interruption of the residual current ywhich ilows after the power switching points have been opened. To obtain an equal voltage distribution over all points of interruption in an air blast circuit breaker, a

choke coil or condenser can be connected in par allel with each rupturing point, or all these points oi interruption can be bridged over by high ohmic reslstances. The choke coils, condensers or resistances can be arranged both inside and outside the extinguishing chambers which enclose the points of interruption.

For a better understanding of the invention, reference is made to the accompanying drawing wherein a preferred constructional embodiment of the invention is shown by way oi illustration, and wherein:

Fig. 1 is a diagrammatic view in side elevation, with parts in section, of an air blast multiple interruption circuit breaker embodying the. invention;

Fig. 2 is a fragmentary vertical section, on an enlarged scale, of one of the arcing chambers oi' Fig. 1; and

Fig. 3 is a central vertical section through another form of arcing chamber.

l The circuit breaker comprises a plurality oi.' arcing switch contact assemblies. identified generally by reference numerals la to Ih, respectively, which are arranged in two groups and mounted on the hollow castings' 2. 2' at the tops of the insulator columns 3, 3'. The contact assemblies la and ih have terminalsy 4, I' for connection to a power line L and a branch line L', respectively, and the contacts of each group are in series with each other and with a disconnecting switch comprising switch blades l, l that are pivotally mounted on the respective insulator heads 2, 2'. The'insulator columns 3, 3 are carried by a truck or portable framework in which the hollow longitudinal members 3 serve as compressed air containers, while the cross members of the frame are each provided with an air passage 1 and a pilot valve l for admitting pressure air to the piston 9 of the blast valve Il that controls the flow of pressure air to the operating mechanism of the circuit interrupter. A large diameter pipe Il extends upwardly through each insulator column to connect the outlet side of the blast valve Ill to the lower end of a passage i2 that extends through the insulator head and opens into the base of v the associated arcing switch contact assembly. A smaller pipe I3 extends upwardly through each insulator column to supply pressure air to the operating mechanism, i. e. the piston Il of the disconnect switch. The control valves and air passages associated with the insulator column 3 are not shown in the drawing, but are substantial duplicates of the valves and passages illustrated in connection with the insulator column 3 and the group of switch contacts la to Id.

Each switch contact assembly is substantially identical with the assembly Ic that is illustrated on an enlarged scale in Fig. 2. The arcing chamber for the contact assembly is formed by a cylindrical insulator Il, a lower metal disk I6 upon which the insulator rests and an upper metal disk IB that is supported by the insulator. Each metal disk II has a passage Il extending laterally from the outer edge oi the disk to the central part where it opens downwardly through a nozzle contact I.. The cooperating pin contact i! of each switch assembly is carried by a piston 2l that slides within a cylinder 2| fixed to the upper face of the next lower disk I0. The piston is normally held in circuit-closing position by spring 22, and the cylinder walls have openings 23 for admitting pressure gas from the arcing chambers to force the piston into circuitopening position. Each of the intermediate metal disks i8 serves as the top wall of one chamber and the bottom] wall of the next higher chamber, and the disks have one or more transverse openings 23 that place all of the chambers of a group in direct communication. The passages I1 or the nozzle contacts Il of the lowest disk I6 of each group may be closed toavoid a waste of pressure gas.

The sets of arcing contacts are bridged overA by impedances of relatively high magnitude, for example by the ohmic resistances 25a to 25h that serve solely to control the potential gradient along the arcing contacts during the circuit breaking operation. After the circuit is opened at the arcing contacts, the residual current flow through the resistances 25a to 25h is interrupted by the opening of the disconnect switch 5, Since the disconnect switch is opened immediately after the arcs are extinguished at the arcing contacts I9, 20, the time during which the residual current iiows through the resistances is ofvery short duration so that there can be no detrimental effects on the circuit breaker.

The circuit breaker is operated by opening the pilot valves, either manually or automatically, to admit pressure air to the piston 9, thereby opening the blast valve II! to. admit pressure air to pipes 'Il and I3. Pressure air enters thestacks of arcing contact assemblies and forces the pistons 22 downward to separate the contacts I8, I9, and pressure air then escapes through the nozzle contacts I1 to extinguish the arcs that are drawn between the contacts. The current damping resistors 25a-25h carry a small residual current after the arcs are extinguished and this residual current is interrupted by the disconnect switch 5, 5'. 'I'he relative sizes of the pipes II and I3 are such that vthe setsof arcing contacts are opened and the arcs are extinguished before the piston Il is displaced to open the disconnect switch.

As shown in Fig. 3, the arcing contacts I8', I9"may both be of nozzle form or tubular for the escape of the gas blast in opposite directions from the gap established upon a separation of the contacts. Both` contacts of each cooperating pair may be movable or, as illustrated, the lower tubular contact I8 may be integral with the metal plate 26 that forms the bottom wall of the arcing chamber and carries the insulator I5' that constitutes the side wall. lA piston 20' carries the movable contact I9 and slides in a cylinder 2I1" that is integral with the metal plate 21 that forms the top wall of the arcing chamber. Openings 23 in the cylinder wall admit pressure gas from` the arcing chamber to lift thepiston against the pressure of the spring 22'. The high impedance for establishing a uniform voltage gradient across the series gaps of lthe circuit breaker may take the form of layers '28; 29 .of semi-conductive material that are sprayed or lotherwise applied to the inner and outer surfaces, respectively, of the insulator I5'.

A spacer member or metal disk 30 is arranged 'between adjacent arcing chambers to provide the inlet and outlet passages for the chambers when, as shown, the top and bottom walls -are formed of relatively thin plates. The spacer members have transverse openings 3I that aline with ports 24a, 2lb in the top and bottom walls 26, 21, respectively, to complete the inlet passages to 33 at its opposite faces that communicate with the bores of the tubular contacts I8', I9', respectively.

It instead of the resistances shown in the drawing, condensers are used to obtain the desired voltage distribution, .then the parts of the the 4several arcing chambers, and grooves 32,

extinguishing chambers enclosing the points of interruption can be used as condenser elements. The walls I3, IB of the extinguishing chambers can be employed as the elements of condensers by forming the hollow insulators I5 of a material with a dielectric constant greater than III. The mutual capacity of the condenser elements connected in parallel with the points of interruption can then be adjusted by varying the shape and size thereof. s

.The design and location of the valve mechanism is not critical and other arrangements may be employed to admit pressure gas to the arcing chambers to separate the several arcing contacts and to the operating cylinder or cylinders that control the disconnecting switch.

Although preferred constructional forms'of the invention have been shown and described by'way of illustrationit will be understood that various modications of the detailsof construction may be resorted to without depafrting from the spirit of the invention within the sdope of the appended claims. l

I claim:

r. In a circuit breaker, a vertical supporting insulator, a plurality of arcing chambers in axial alinement with and superposed upon said insulator, each arcing chamber comprising a hollow insulator forming the circumferential wall of the chamber and.meta1 plates forming the top and bottom walls thereof, inlet passages for admitting pressure gas to each chamber, a pair of arcing contacts within each chamber and electrically connected to the top and bottom walls thereof, pistons slidable in cylinders within the respective chambers and carrying one contactr of each pair, spring means urging said pistons towards circuit closing position, an opening in the wall of each cylinder to admit pressure gas from the chamber to actuate the piston to circuit opening position, one of said contacts being of nozzle form, and an outlet passage extending from said nozzle form contact to atmosphere to establish a gas blast for extinguishing the arc drawn by a separation of the contacts.

2. In a circuit breaker, the invention as claimed in claim l, wherein said hollow insulators include means for establishing a predetermined voltage gradient; across the arcing-contacts of the several arcing chambers.

3. In a circuit breaker, the invention as claimed in claim 1, wherein -said hollow insulators include a semi-conducting layer at one face thereof for establishing .a predetermined voltage gradient across the arcing contacts of the several arcing chambers.

4. In a circuit breaker, the invention as claimed in claim l, wherein said hollow insulators include a semi-conducting layer at both faces thereof for establishing a predetermined voltage gradient across the arcing contacts of the several arcing chambers.

5. In a multiple break gas blast circuit breaker, a plurality of axially alined and superposed arcing chambers, each chamber comprising a hollow insulator and metal plates extending across the endsfthereofto formthe top and bottom walls offthechamber, a cylinder within each chamber arid'carried'by one metal plate thereof, a piston within each cylinder and carrying an arcing contact, a cooperating contactl carried by the other metal plate of each chamber, spring means urging the respective pistons towards circuit closing position, means defining inlet passages for admitting a pressure gas to each chamber and the associated cylinder, a contact of each assothe invention as claimed in claim 5, wherein a single metal plate .extends across the ends of adjacent hollow insulators to form the end walls of adjacent arcing chambers.

7. In a multiple break gas blast circuit breaker,

vthe invention as claimed in claim wherein a single metal plate extends across the ends of adjacent hollow insulators to form the end walls of adjacent arcing chambers, and the metal plate between adjacent arcing chambers has a transverse passage for the escape of the pressure gas from the nozzle form contact.

8. A switching arrangement comprising a circuit breaker and a disconnect switch inserles. said switching arrangement including a pair of supporting insulators. a plurality of extinguishing chambers mounted in supperposed relation on each` of said insulators, a pair of gas blast extinguished arcing contacts arranged in each extinguishing chamber and connected in series to form a group of circuit breaker units on each insulator, said extinguishing chambers each comprising a cylindrical'insulator forming the side wall of the chamber and m'etal top and bottom walls with inlet and outlet openings for the admission and exhaust of compressed gas, voltage drop distributing means connected across each pair of arcing contacts, means connecting the disconnect switch in series between said groups of circuit breaker units on the respective insulators, means operable by pressure gas to open said disconnect switch, a source of pressure gas, and valve means for admitting pressure gas to said extinguishing chambers and to` said switch-operating means, therebyto separate said arcing contacts and to open said disconnect switch.

9. A switching arrangement according to claim 8 in which a supporting frame is provided for said insulators, said frame comprising longitudinal members formed u containers for compressed gas for operating said switching arrangement.

l0. In a switching arrangement according to claim 8, said insulators being hollow members, and pipes for the supply of compressed gas for operating said arcing contacts and said disconnect sr-'itchv are disposed in said hollow insulators.

ll. In a multiple break gas blast circuit breaker, a plurality of axially alined and superposed arcing chambers, each chamber comprising a hollow insulator and metal members extending across the ends thereof to form the top and bottom walls of the chamber, a set of cooperating and relatively movable contacts within each chamber and carried by the top and bottom walls thereof, one contact of each set being a nozzle contact and the metal member carrying the same having a transverse passage for the escape of pressure gas from the nozzle contact,

means yieldingly maintaining the cooperating contacts in engagement, means within each chamb`er and responsive to gas pressure to separate the cooperating contacts of that chamber, and passages through said metal members for admitting pressure gas from one chamber to the next.

l2. In a multiple break gas blast circuit breaker, the invention as claimed in claim ll, wherein a single metal member is arranged between -adjacent hollow insulators to form the end walls of adjacent arcing chambers.

13. In a multiple break gas blast circuit breaker, the invention as claimed in claim 11, wherein said hollow insulators comprise material havng a dielectric constant greater than l0, whereby the metallic end walls and hollow insulator of each arcing chamber constitute a condenser for establishing a predetermined. voltage gradient across the set-s of cooperating contacts upon separation oi' the same.

HANS THOMMEN. 

